下列鉴别方法或除杂可行的是（ ）
A．用新制的氢氧化铜鉴别乙醛、甲酸、乙酸、己烯
B．用溴水鉴别乙醇、苯、环己烯、苯酚，甲苯
C．除去苯中混有的苯酚，加入溴水后过滤
D．检验丙烯醛（CH2=CHCHO）中的醛基，加入溴水，若溴水褪色，则证明含有醛基
答案：A
题目分析：A、乙醛和新制的氢氧化铜加热能看到砖红色沉淀，甲酸和新制的氢氧化铜先使其溶解，加热有砖红色沉淀，乙酸和新制的氢氧化铜使其溶解，己烯不反应，正确；B、苯和甲苯都能把溴萃取到上层，下层无色，这二者无法鉴别，错误；C、溴易溶于苯，引入新的杂质，错误；D、加入溴水，碳碳双键和醛基都有还原性，可使其褪色，因此不能起到证明醛基的效果，错误。
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| Back in my country, when I was a child, I used to go to "market day" with my mother. One day each week, farmers used to 1 their fruit and vegetables into the city. They 2 one street to all cars, and the farmers set up tables for their 3 . This outdoor market was a great place to 4 . Everything was fresher than produce in grocery stores because the farmers brought it in 5 after the harvest. My mother and I always got there early in the morning to get the 6 produce. The outdoor market was a wonderful adventure for a small child, 7 was like a festival-full of colors and 8 . There are red tomatoes, yellow lemons, green lettuce, peppers, grapes, onions. The farmers did their-own 9 . They all shouted loudly for 10 to buy their produce. "Come and buy my beautiful oranges! They're juicy and delicious and full of vitamins to 11 your children healthy and strong!" Everyone used to 12 with the farmers over the 13 of their produce. It was like a wonderful drama in a theatre; the buyers and sellers were the " 14 " in this drama. My mother was an 15 at this. First, she picked the freshest, most attractive tomatoes, for example. Then she asked the price. The seller told her. "What?" she said. She looked very surprised. "So 16 ?" The seller looked terribly 17 . "My dear lady!" he replied. "I'm a poor, 18 farmer. These are the cheapest tomatoes on the market!" They always argued for several minutes before agreeing 19 a price. My mother took her tomatoes and left. Both buyer and seller were 20 . The drama was over. | ||||
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